Chemical kinetics in carbon depositing d.c.-arc jet CVD reactors

Experimental and theoretical studies of the behaviour of hydrocarbon species in d.c.-arc jet chemical vapour deposition reactors are reported, as a function of carbon source gas flow rate. CH(X) and C (a) radical number densities have been measured in2 absorption (by cavity ring-down spectroscopy) and via their optical emission in an arc jet plume operating with a standard CH y4 H yAr feedstock gas mixture. The C (a) radical number density is seen to exhibit a linear (or sub-linear) dependence on CH2 2 4 flow rate, in accord with previous findings (J. Appl. Phys. 82 (1997) 2072) for both C (a) and C (X) radicals in a lower power2 3 d.c.-arc jet. The present findings, together with the comprehensive set of earlier experimental data on gas velocity and ga